Control of urinary risk factors of stones by betulin and lupeol in experimental hyperoxaluria

Urolithiasis, the process of formation of stones in the kidney and the urinary tract, is the major clinical manifestation of hyperoxaluria. Crystal deposition, as indicated by increased stone-forming constituents in urine, such as calcium, oxalate and uric acid, and decreased concentration of inhibitors, such as magnesium and glycosaminoglycans, was observed in pyridoxine-deficient hyperoxaluric rats. Renal tubular damage was indicated by increased excretion of enzymes such as alkaline phosphatase, lactate dehydrogenase, gamma-glutamyl transferase, beta-glucuronidase and N-acetyl glucosaminidase. Fibrinolytic activity was found to be reduced. Administration of pentacyclic triterpenes such as lupeol and its structural analogue betulin to hyperoxaluric rats minimised the tubular damage and reduced the markers of crystal deposition in the kidneys. In this connection, lupeol was found to be more effective than betulin.